# Tagged Questions

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### Why is my reasoning wrong in determining how many functions there are from set A to set B?

I am trying to count how many functions there are from a set $A$ to a set $B$. The answer to this (and many textbook explanations) are readily available and accessible; I am not looking for the ...
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### Proving a bijection(injection and surjection) over a function

I need some help proving bijections: Suppose f is a function from $$\mathbb R^2 \rightarrow \mathbb R^2$$ Defined by $$f(x,y) = (ax-by,bx+ay)$$ Where a,b are numbers with $$a^2 + b^2 \neq 0$$ ...
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### Sets Theory Disproof

I have to disprove the statement: For all sets $S$, if $S$ is a subset of the Natural Numbers, then there must exists some $t ∈ S$ such that $|t|\ge1$ Any hints?
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### How to show that $A-(B\cap \overline {C})\subseteq A\cup (B\cap C)$ [on hold]

How do I solve this? Let A, B and C be sets. Show that $A-(B\cap \overline {C})\subseteq A\cup (B\cap C)$ I can't figure it out. Could I use venn or karnaugh?
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